We need an Upside Down button!
Indeed. There seems to be some misunderstanding about what the rotate function does and what @rwiesmann wants.
First, what the rotate button actually does:
After (sorry I was lazy and just flipped the image myself, ignore the timestamp):
Imo this doesn't make much difference for most users as it's a 360° view, the initial view when changing to DPTZ view is different, but that's about it I think.
What the OP needs is to flip the DPTZ image the right side up when the camera is not ceiling mounted but floor/desk/whatever else mounted. So flip this around:
I hope that clears up the confusion...